This invention relates to medical and industrial devices used for administering or receiving fluids to or from a patient, area or process and more specifically to a hypodermic syringe with a mechanical system for automatically retracting the needle into the syringe, thereby rendering the syringe useless and safe for handling and transport to disposal.
Current designs for monouse syringes do not allow for the inadvertent or accidental puncture of health care, laboratory and industrial users who come in contact with an exposed needle. Monouse syringes can be used as many times as desired despite labeling and warnings to the contrary. Furthermore, current patented designs for retractable needle type syringes are at best poor in their solutions to the problem of conveying or retracting the needle from the operational condition to a protected or enclosed condition. Some even fail to address covering the needle prior to use. U.S. Pat. No. 4,838,869 to Allard and U.S. Pat. No. 4,955,870 to Ridderheim et al. disclose a means whereby the needle assembly acting as a piston is retracted aft by a spring under tension into a cylindrical chamber within the structure of the plunger and illustrates no means to prevent the pressurization of air trapped in the chamber by the rapidly retracting needle assembly. Clearly, this would miss a basic mechanical need to provide for venting the cylinder to allow air trapped in the cylinder to escape.
These and other weaknesses in the current art designs coupled with economic considerations for manufacture may not permit a viable solution to be available in the market for some years to come. The incidence of injury to life and health by accidental puncture and cross contamination of persons using, handling, or in close proximity to syringes having exposed contaminated needles is greater now than ever before. The need for a safe, reliable, inexpensive, and manufacturable retracting needle syringe is of significant importance.